Muscle Disorders Flashcards
What are some clinical signs of rhabdomyolysis or “tying up”?
Reluctance to move, muscle stiffness, muscle cramping, muscle pain, swelling
-very similar to colic signs/laminitic signs
What are the signs associated with muscle atrophy?
Decrease in muscle mass, can be focal or diffuse or acute or chronic
What are the clinical signs associated with muscle weakness?
Reluctance to move, difficulty getting up, stumbling/dragging toes
Describe the pathogenesis of rhabdomyolysis
-Aberrant calcium cycling
-excessive calcium accumulation in muscle cell, mitochondria attempts to sequester calcium, overwhelmed mitochondria produces free radicals, phospholipases, and inflammatory cytokines
-muscle cell capable of repair if basal lamina remains intact
-repair begins in 16-48 hours
-cells completely repaired in 30 days
What are the different types of muscle atrophy?
Overt muscle damage
Myogenic- activation of internal machinery that destroys cells (affects type 2 fibers)
Neurogenic- type 1 and type 2 muscle fibers affected
What causes muscle fasciculations?
Abnormal recruitment of nerves due to nerve root irritation, electrolyte abnormalities, weakness, fatigue, anxiety/pain, cold
-OR ion channel defects within the sarcolemma as with HYPP
What is the main breed affected by HYPP?
Quarter horses
-through the impressive line
When should you run the serum CK exercise response test?
If exertional rhabdomyolysis is suspected
-try to provoke subclinical ER
-run CK baseline and then after 4-6 hours after exercise. If 3X increase from baseline this is a positive
What electroyte changes can be seen with horses with moderate/severe rhabdomyolysis?
Hyponatremia, hypochlorema, hypocalcemia, hyperkalemia, hyperphosphatemia
What can myoglobinuria be associated with?
Renal tubular necrosis
What occurs in horses with polysaccharide storage myopathy
Inability to use glycogen- sequestered in muscle
